Fungi Eukaryotic Organisms

Fungi  Mycology: The study of fungi.  Fungi: A diverse group! Can be… Heterotrophic: Any organism that cannot synthesize its own food. Saprophyte: Any organism that derives nourishment from dead or decaying matter. Parasite: Any organism that obtains nutrients from the tissues of another organism it lives in or on.  Most are multicellular, complex organisms. Yeast: A variety of unicellular, fermenting fungi.

Fungi Anatomy  Cell Walls: Some fungi have cellulose walls, but most have chitin (a polysaccharide). Chitin is also found in exoskeletons! E.g., ticks & spiders.  Enzymes: Lysosomal enzymes are found in all fungi & digest damaged cells & aid in host invasion.

Fungi Anatomy  Pileus aka Cap: The horizontal portion of a mushroom containing the lamellae, tubes, and scales. Lamellae aka Gill: A radiating vertical plate on the underside of a mushroom cap of some mushrooms. Scale: Thin, flat plates on the cap of a mushroom

Fungi Anatomy  Stape aka Stem: The portion of the mushroom that grows in the opposite direction of the roots and provides support for the above-ground portion of the fungi.  Annulus aka Ring: The growth ring or veil remnant on a mushroom stalk – surrounds the stem of a mature mushroom.  Volva aka Cup: A membranous envelope enclosing the base of various mushrooms.

Fungi Anatomy  Mycelium: A loosely organized mass of hyphae. Stays embedded in decaying organic matter, soil, or living tissues. Mycelial cells release the enzymes that digest the substratum (surface the fungi is growing on) & absorbs small molecules. Hyphae: Threadlike structures that combine to form the mycelium.  Hyphal cells are typically have two nuclei.  Septa: The cross-wall structure that divides the two halves of the hyphal cells.  Septa allow cytoplasm & nuclei to pass between the cells.

Fungi Anatomy  Thallus: The body of fungi that has not differentiated into leaves, stems, roots, etc.

Types of Fungi

Edible Cultivated Mushrooms

Edible Wild Mushrooms

Medicinal Mushrooms

Poisonous & Psychotropic Mushrooms

Fungal Reproduction  Asexual Reproduction: Reproduction that does not involve the union of gametes or the exchange of genetic material. Conducted through Mitosis or Binary Fission.  Sexual Reproduction: Reproduction that involves the union of gametes and the exchange of genetic material. Conducted through Meiosis.  Fungi can reproduce both sexually and asexually. A few ONLY reproduce asexually. This includes yeast!

Asexual Reproduction – Mitosis  Mitosis: The process of cell division resulting in two identical daughter cell produced from a single parent cell. Prophase: The chromatin within the cell condenses into chromosomes and divides. Metaphase: The chromosomes align at the equitorial plate & attach to the cell wall & centromere via the mitotic spindle. Anaphase: The centromere divides, splitting the chromosomes. The chromosomes migrate to opposite poles. Telophase: The cell membrane pinches inward, dividing the cytoplasm, & splits into two complete cells.

Asexual Reproduction – Binary Fission  Binary Fission: A method of asexual reproduction very similar to mitosis. DNA of the mother cell replicates & joins into circular pairs. The circular pairs attach to the cell membrane/plasma membrane. The cell elongates, forcing the paired chromosomes separate. The cell membrane invaginates (pinches inward toward the middle). When the cell membrane has completed invaginating, the cell splits off into two identical daughter cells. It is fairly common for one of the daughter cells to not be identical to the mother cel.

Sexual Reproduction – Meiosis  Meiosis: A method of sexual reproduction where germ cells (such as eggs and sperm) are produced. The total amount of genetic material in the daughter cells is reduced during division. 4 daughter cells with a single set of chromosomes is produced. The cell must join with another daughter cell with a second set of chromosomes to divide into a new organism.

Sexual Reproduction – Meiosis  First Division of Meiosis: Interphase: Genetic material duplicates. Prophase 1: The duplicated genetic material condenses and pairs off, then may go through “crossing-over” to exchange segments between the chromosomes. Prometaphase: Nucleus dissolves and mictrotubules attach to the genetic material. Metaphase 1: The chromosomes align at the equitorial plate. Anaphase 1: The chromosome pairs separate, sister chromatids remain together. Telophase 1: Two daughter cells are formed with one chromosome each.

Sexual Reproduction – Meiosis  Second Division of Meiosis: Gametes are formed. Prophase 2: DNA does not replicate Metaphase 2: Chromosomes align at the equatorial plate. Anaphase 2: Centromeres divide into 23-chromosome sets & sister chromatids migrate to opposite poles. Telophase 2: Complete cell division begins.. Cytokinesis: 4 haploid daughter cells are produced, each with 23 chromosomes.

Fungi in the Ecosystem  Facultative Parasite: An organism that can obtain nutrients from nonliving organic matter or from living organisms. Fungi don’t have to be parasitic, but can be if given the opportunity.  Beneficial Behaviors: Act as decomposers. Some fungi produce antibiotics to inhibit the growth of bacteria or kill the bacteria outright.  Penicillin is produced by a fungi from the ascomycota group called a sac fungi.